Hydraulic control device



Oct. 11, 1949. P. AUDEMAR ETAL HYDRAULIC CONTROL DEVICE 3 Sheets-Sheet 1 Filed Sept. 1.8; 1945 OW/L 000/4 Z/JSO y Oct. 11, 1949. P. AUDEMAR ETAL.

HYDRAULIC CONTROL DEVICE 3 Sheets-Sheet 2 Filed Sept. 18, 1945 F G H Pos/r/olv A B C D Oct. 11, 1949. P. AUDEMAR EIAL HYDRAULIC CONTROL DEVICE 3 Sheets-Sheet 3 Filed Sept. 18. 1945.

Patented Oct- 11, 1949 HYDRAULIC CONTROL DEVICE Pierre Audemar, La Garenne-Colombes, and Camille Duchaussoy, Paris, France, assignors to Olaer Patent Cy, Luxembourg (Duchy of Luxembourg), a company of Luxemburg, and Compagnie Generale Pour IEquipement Aeronautiqnc, Paris, France, a company of France Application september 18. 1945, Serial No. 617,078

In France July 11, 1944 Section 1, Public Law 690, August 8, 1946 Patent expires July 11, 1964 Claims. (Cl. I'm-160.19)

The present invention concerns a hydraulic control device which permits of rapidly bringing a part to be controlled into any of a certain.

It is known that a variable pitch propeller must a be able to occupy four main positions:

1. A braking position for landing, in which the blades are given a negative incidence.

2. A braking position for diving, in which the blades have practically an incidence equal to zero;

3. A take of! position, in which the blades have a positive incidence, but of small pitch;

4. The so-called feathered position, in which the blades give the minimum of drag.

Therefore, the variable pitch propeller control device must be capable of bringing the blades of the propeller into one of these four positions, and this as quickly and reliably as possible. It is therefore of interest to work with very high pressures and a high flow rate of a working liquid.

2 spect to one another that, at any time, only one of them can be closed, the three others being open. Furthermore, one of the compartments is constantly fed with fluid under pressure, but the surface of this compartment subjected to the action of the liquid under pressure is the smallest of those on which the pressure acts in the four compartments, this in order to permit the reduction of the volume of this compartment, and, consequently, the elongation of the jack when the liquid is successively admitted into the other compartments. The jack is completed by a system of abutments so as to obtain four well determined relative positions for the elements of the jack, and consequently four positions for the blades of the propeller to be controlled. It will be noted that the abutments can be made adjustable in such manner as to permit of modifying one or the other of the fixed positions. On

On the other hand, between the two last mentioned positions, that is to say the low pitch position :and the "feathered position, the blades must be able to assume any desired intermediate position, this pitch adjustment permitting of running the engine under constant working conditions. In order to obtain this adjustment, it is necessary to limit the rate of flow in such manner as to give the operation all the precision that is desired.

The control device according to the invention complies with these conditions. This device is essentially constituted by a four-position Jack, a source of high pressure and high flow rate bydraulic energy, a system of valves arranged in a particular manner, and a return reservoir. The source of energy is preferably constituted by an accumulator capable of instantaneously supplying a high rate of flow, this accumulator being on the other hand constantly fed from a pump which gradually restores the energy given ofl by the accumulator during its operation. H i

In order to obtain the four positions of the jack, the latter includes four chambers adapted to be fed separately with liquid underpressure. supplied by the source of energy, through four valves arranged and located in such manner with rethe other hand, when the elements of the jack are in position 3 above referred to, they can be displaced with respect to one another so as to pass from said position 3 to position 4 and in versely in such manner as ,to remain for the desired time in any intermediate position. In this case, the feed of liquid takes place through the intermediate of a flow limiter which controls the inflow of liquid under pressure into compartment 4. Finally it will be noted that the control means which permits either of obtaining any of the four desired main positions or of bringing the system into automatic variation working conditions is constituted by a single control organ acting on movable elements mounted in a single valve body arranged in a particular way.

Embodiments of the invention will be described with reference to the annexed drawings on which:

Fig. 1 is a diagrammatic sectional view of a jack forming part of a control device according to the invention, the jack elements assuming one of the four possible main positions;

Fig. 2 is a view similar to that of Fig. 1, showing the elements in the second main position;

Fig. 3 is a view similar to that of Fig. 1, showing the elements in the third main position, and

Fig. 4 is a view similar to that of Fig. 1, showing the elements in the fourth main position;

Fig. 5 diagrammatically shows the control device according to the invention including a source of liquid under pressure, the jack, a return reservoir and four valves controlling the various positions of the jack elements;

Fig. 6 is a table showing the communications of the four compartments of the jack with the source of liquid under pressure and the reservoir in the four positions that can be occupied by the jack elements;

Fig. 7 shows the position of the four valves for the four positions of the jack;

Fig. 8 diagrammatically shows the valve system; I

Fig. 9 is a diagram similar to that of Fig. 5, but including a device for obtaining the gradual displacement of the elements of the jack between the positions shown in Figs. 3 and 4; and

Fig. 10 diagrammatically shows the. system of valves of Fig. 5 modified in such manner as to permit operation according to the diagram of Fig. 9.

Referring first to Figs. 1-4, abcd are the tour compartments of the jack respectively supplied through connections A, B, C and D. As above stated, compartment is constantly supplied with fluid under pressure. In Figs. 1-4 (and also in the tables of Figs. 6 and 7), the sign indicates the orifices that are connected with the admission and a sign indicates the orifices which are connected with the exhaust.

In Fig. 1, only compartment 0 is connected with the admission, the three others being connected with the exhaust. The movable portion of the jack therefore occupies the position that is most on the left hand side, that is to say the retracted position corresponding to braking on landing, during which the blades have a negative incidence.

In Fig. 2, liquid under pressure is admitted also into compartment b. In view of the fact that the area of the movable wall 2 on which acts the liquid of compartment 1) is larger than the area of the movable wall I on which acts the liquid that is present in compartment 0, the whole of the movable elements of the jack is pushed from left to right, in such manner that the extreme right hand wall 3 of the jack comes to occupy the position shown in Fig. 2, which corresponds to dive braking, in which the blades of the propeller have a zero incidence. This position is determined by an abutment 6 provided on the inner cylindrical wall 1 of compartment b coming into contact with the rear partition of the jack body.

In Fig. 3, the liquid under pressure is further admitted into compartment d and pushes, on the one hand, the wall I, the right hand face of which is smaller than its left hand face, and, on the other hand, wall 3, toward the right. This thrust is limited by an abutment in such manner that the position shown in Fig. 3 is also determined in a precise manner. The position shown in Fig. 3 corresponds, as above stated, to take oil, when the propeller blades are to have a positive but small pitch incidence.

Finally, in order to obtain the position shown in Fig. 4, that is to say the "feathered" position, liquid under pressure is admitted into compartment a, this liquid coming to act on wall 3 and moving it away from wall 2 until wall I comes into contact with the right hand partition 9 of the jack body. At this time, the Jack has the maximum elongation.

Fig. 5 digrammatically shows the whole of the +ithe orifices that are connected with the admission and by sign the orifices that are connected with the exhaust, for each of the four positions 'of the jack. As shown by this table, in position I, only orfice C is connected with the admission, the others being connected with the exhaust. In the position shown in Fig. 2, orifices B and C are connected with the admission and orifices A and D with the exhaust. In the position shown in Fig. 3, orifices B, C and D are connected with the admission and A with the exhaust and in the position shown in Fig. 4, the four orifices A, B, C, D are connected with the admission.

' In order to obtain this result in a simple way and by means of a single control, valves E, G, H, F are disposed in series and are arranged in such manner that only one of these valves can be closed at a time, the three others being open. The table of Fig. 7 indicates, for the four positions, the opening and the closing of the various valves, sign indicating the open valves and sign the closed valve. It will be seen that, in the position shown in Fig. 1 only valve Ewhich is the first of the series-is closed, while, in the three other positions, the valves that are successively closed are valves G for the position shown in Fig. 2, H for the positon shown in Fig. 3 and F for the position shown in Fig. 4.

Fig. 5 shows an embodiment of a group of valves assembled in a single body and controlled in a simple manner by a single control organ. On this drawing, the-valve body is shown at 9 andthe liquid inlet under pressure at H). Compartment c is fed directly from the accumulator and, as above stated, is constantly under pressure. might, if so desired, be separately fed with any fluid under suitable pressure. In the body 9 of the valve, are mounted four slide valves E, G, H and F representing the four valves above referred to. Slide valve E is located in the passage extending from orifice l0 toward the inlet orifice B. Slide valve Gcontrols the flow of liquid under pressure toward inlet orifice D. Slide valve H controls the inlet Orifice A and slide valve F the return toward the reservoir. These four slide valves are controlled by a sliding cam ll movablein the direction of arrow l2; this cam can be controlled in any suitable manner. Cam II, which extends through rings l3, l4, l5 and I6, connected respectively with the four slide valves E, G, H and F, includes a stepped portion arranged in such manner that,

- when the ring of one of the valves is on this stepped portion (ring l5 of valve H in Fig. 8), the corresponding valve is closed. In Fig. 8, the position of the valves corresponds to the position shown in Fig. 3 of the jack in which the valve that is closed is H. When cam II is displaced in one direction or the other, each of the valves is successively closed, the others being open.

device, including an accumulator S fed by means of a piping T through any pump, not shown, a jack the whole of which is indicated by letter V, a return reservoir indicated by letter R, and four valves, respectively E, G, H and F. A, B, C and D are the inlet and outlet orifices corresponding to compartments a, b, c and d of the jack.

Fig. 6 is a table in which are indicated by sign As stated at the beginning of the description, the jack must not only assume four well determined positions, but still be able to assume any desired position between the positions shown in Figs. 3 and 4. Consequently, as soon as the jack has been brought into the position shown in Fig.

3, it must be able to be automatically controlledby a regulating device rigid-with the engine. As above stated, in the position shown in Fig. 3, only valve H is closed.

Fig. 9 diagrammatically shows a device for placing the variation of volume of compartment a under control of a regulating device. This figure corresponds to the system of Fig. 5 completed As a matter of fact, this compartment by a three way cock K inserted between orifice A on the one hand and a point X of the conduit extending between valves H and F on the other hand. This cock K is on the other hand connected with a distributing device which permits of connecting compartment a either with the source of energy, or with the return reservoir. This circuit includes a flow limiting device L and a slide valve M controlled by a regulating element N. Cock K is synchronized with valve H in such manner that, when H is closed, valve K connects the compartment a of the jack with distributin device M through the intermediate of the flow limiter L, while cutting ofi the communication between A and the point X of the conduit extending between valves H and F. On the contrary, when valve H is open, cock K connects orifice A with point X, distributing device M being placed out of circuit. To sum up, when valve H is closed, A communicates, through valve K, with distributin device M, and when H is open, A is directly connected with point X of the conduit extending between valves H and F. The fiow limiter L is provided so that the displacement of the jack between the positions shown in Figs. 3 and 4 may be slowed down thus ensuring the necessary precision of operation. Regulating device N is controlled by the propeller shaft, distributing device M being made, for instance, in the form of a slide valve distributor of any suitable type.

Fig. shows the group of valves of Fig. 8 modified in such manner as to obtain the synchronizing of the working of three way cock K with that of valve H. In this figure, K is a slide valve mounted in line with the axis of slide valve H, tube I1 communicating with orifice A, tube II with the flow limiter L and tube .IS with point x (see Fig. 9) located between valves H and F.

It should be well understood that the invention is not limited to the embodiment shown and described. In particular, instead of controlling the four valves by means of a single organ, each of the valves may be provided with a separate organ such as an electro-valve, a push-button, etc., provided that they are arranged in such manner that only one of the valves is closed, the others being open.

In a general manner, while we have, in the above description, disclosed what we deem to be practical and efficient embodiments of the present invention, it should be well understood that we do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

What we claim is:

1. A hydraulic control device comprising in combination a motor unit in the form of a jack including a cylinder, a main piston and two auxiliary piston members slidably mounted in said cylinder adapted to form therewith four chambers, the successive filling of which with liquid corresponds to different positions of said main piston, a source of liquid under pressure, a discharge, a pipe between said source and said discharge, four conduits extending between said chambers and four distinct points of said pipe, each conduit connecting one chamber to one corresponding point, four valves mounted on said pipe, three of them each between a pair of said four points and the fourth between said discharge and that of said four points which is the nearest to said discharge, and means for operating said valves so as always to have one of them closed and the three others open.

2. A hydraulic control device comprising in combination a motor unit in the form of a jack including a cylinder, a main piston and two auxiliary piston members slidably mounted in said cylinder adapted to form therewith four chambers, the successive filling of which with liquid corresponds to different positions of said main piston, a source of liquid under pressure, a discharge, a pipe between said source and said discharge, four conduits extending between said chambers and four distinct points of said pipe, each conduit connecting one chamber to one corresponding point, four valves mounted on said pipe, three of them each between a pair of said four points and the fourth between said discharge and that of said four points which is the nearest to said discharge, means for operating said valves so as always to have one of them closed and the three others open, a three-way valve inserted in the circuit leading to the third of said points, a conduit starting from said three-way valve, disstributing means for placing said last mentioned conduit in communication with either said source or said discharge, and means for operatively connecting said three-way valve with the third of said four valves to permit adjustment of the position occupied by the main piston between at least two of predetermined positions.

3. A hydraulic control device comprising in combination a motor unit in the form of a jack including a cylinder, a main piston and two auxiliary piston members slidably mounted in said cylinder adapted to form therewith four chambers, the successive filling of which with liquid corresponds to different positions of said main piston, a source of liquid under pressure, a discharge, a pipe between said source and said discharge, four conduits extending between said chambers and four distinct points of said pipe, four valves-mounted on said pipe, means for operating said valves, a three-way valve inserted in the circuit leading to the third of said points. a conduit starting from said three-wayvalve, distributing means for placing said last mentioned conduit in communication with either said source or said discharge, means for operatively connecting said three-way valve with the third of said four valves, and flow rate limiting means insorted in said last mentioned conduit.

4. A hydraulic control device comprising in combination a motor unit in the form of a jack including a cylinder, a main piston and two auxiliary piston members slidably mounted in said cylinder adapted to form therewith four chambers, the successive filling of which with liquid corresponds to difierent positions of said main piston, a source of liquid under pressure, a discharge, a pipe between said source and said discharge, four conduits extending between said chambers and four distinct points of said pipe, each conduit connecting one chamber to one corresponding point, four valves mounted on said pipe, three of them each between a pair of said four points and the fourth between said discharge and that of said four points which is the nearest to said discharge, means for operating said valves so as always to have one of them closed and the three others open, a three-way valve inserted in the circuit leading to the third of said points, a conduit starting from said three-way valve, distributing means for placing said'last mentioned conduit in communication with either said source or said discharge, and a rod rigidly connecting said three-way valve with the third of said four valves. 1

5. The combination with a variable pitch propeller, of a hydraulic control device as claimed in claim 1 for' moving the blades to any one of tour definite positions, and means for automatically adjusting the osition occupied by the blades between at least two of said definite positions.

PIERRE AUDEMAR. CAMILLE DUCHAUSSOY.

8 REFERENCES crmn The following references are of record in the file of this patent:

UNI'IED STATES PATENTS Number Name Date Pelton June 18, 1935 Rindfleisch Sept. 30, 1941 Thornhill Aug. 18, 1942 Martin et a1 Sept. 22, 1942 Clench Oct. 20, 1942 

